The present invention is related to the field of designing and manufacturing of dental restorations such as crowns, bridges, copings, abutments and implants. When a patient requires a dental restoration the dentist will prepare the teeth e.g. a damaged tooth is grinded down to make a preparation where the crown is glued onto. An alternative treatment is to insert implants (titanium screws) into the jaw of the patient and mount crowns or bridges on the implants.
CAD technology for manufacturing dental restorations is rapidly expanding resulting in improved quality, reduced cost and facilitation of the possibility to manufacture in attractive materials otherwise not available. The first step in the CAD manufacturing process is to create a 3-dimensional dental model of the patient's teeth. This is provided by 3D scanning of one or both of the dental gypsum models or by scanning impressions of the teeth. The 3-dimensional replicas of the teeth are imported into a CAD program, where the entire dental restoration or a bridge substructure is designed. The final restoration 3D design is then manufactured e.g. using a milling machine, 3D printer, rapid prototyping manufacturing or other manufacturing equipment. Accuracy requirements for the dental restorations are very high otherwise the dental restoration will not be visual appealing, fit onto the teeth, could cause pain or cause infections.
Systems for designing dental restorations are known in the art, e.g. 3Shape DentalDesigner™ and 3Shape AbutmentDesigner™, which are generally used by dental specialists such as dental technicians. Users of such design tool systems are working with a three dimensional dental model of the patient trying to fit the dental restoration model into the dental model. During dental restoration of a patients teeth the typical procedure could be to secure an implant abutment in the jaw of the patient, a coping is then attached (e.g. by glue) to the abutment and finally a crown is glued onto the coping. However, both abutment, coping and crown must be designed to fit the patient, both physically and visually. I.e. the abutment, the coping and the crown must be customized for each tooth of each patient.
In the following the term “dental restoration” can be an implant abutment, a coping, a crown or any combination of these. Correspondingly a “dental restoration model” can be an abutment model, a coping model, a crown model or any combination of these.
In the design phase of a dental restoration a three dimensional model of the dental restoration is typically provided by the system and the task of the dental specialist is to shape the dental restoration model to provide a perfect fit in the dental model, whereby the patient can end up with a tooth implant that matches the other teeth of the patient. A dental specialist (i.e. a user of the system) is typically working with a dental model with at least one attached dental restoration model on a screen and the 3D models can typically be rotated around any axis, zoomed, panned and the like. Thus the user will typically be able to specify and change the orientation and viewing angle of the dental model and the dental restoration model. The task of a user is to shape and customize the dental restoration model into the dental model by translating, rotating, dragging, tilting, widening and/or narrowing the 3D dental restoration model (which preferably is fixed in the dental model). This is typically provided by use of an electronic screen pointing tool, such as a mouse, a ball pen or the like. In the following any reference to a “mouse cursor” or a “mouse marker” is a reference to the element on the screen representing the electronic screen pointing tool.
The dental restoration model can be customizably shaped by means of the pointing tool by shaping (“dragging”) the dental restoration model with origin in specific points on the dental restoration model. These points are in the following termed “control points” and can be seen in FIG. 1. The control points are typically located in carefully and preferably automatically selected positions on the dental restoration model. For example in FIG. 1 showing an abutment model where the control points are located on the top center, each of the four sides and around the lower bottom rim (i.e. the lower collar of the abutment).